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Abstract

Background

While obesity is known to have many physiological consequences, the psychopathology
of this condition has not featured prominently in the literature. Cross-sectional
studies have indicated that obese children have increased odds of experiencing poor
quality of life and mental health. However, very limited trial evidence has examined
the efficacy of exercise therapy for enhancing mental health outcomes in obese children,
and the Sheffield Obesity Trial (SHOT) will provide evidence of the efficacy of supervised
exercise therapy in obese young people aged 11–16 years versus usual care and an attention-control
intervention.

Method/design

SHOT is a randomised controlled trial where obese young people are randomised to receive;
(1) exercise therapy, (2) attention-control intervention (involving body-conditioning
exercises and games that do not involve aerobic activity), or (3) usual care. The
exercise therapy and attention-control sessions will take place three times per week
for eight weeks and a six-week home programme will follow this. Ninety adolescents
aged between 11–16 years referred from a children's hospital for evaluation of obesity
or via community advertisements will need to complete the study. Participants will
be recruited according to the following criteria: (1) clinically obese and aged 11–16
years (Body Mass Index Centile > 98th UK standard) (2) no medical condition that would restrict ability to be active three
times per week for eight weeks and (3) not diagnosed with insulin dependent diabetes
or receiving oral steroids. Assessments of outcomes will take place at baseline, as
well as four (intervention midpoint) and eight weeks (end of intervention) from baseline.
Participants will be reassessed on outcome measures five and seven months from baseline.
The primary endpoint is physical self-perceptions. Secondary outcomes include physical
activity, self-perceptions, depression, affect, aerobic fitness and BMI.

Background

The prevalence of obesity has reached alarming levels in Britain with several studies
[1] reporting that the number of young people who are overweight and obese has increased
notably over the past decade. This dramatic increase in overweight has not been confined
to British children and adolescents; pediatric overweight is also increasing in other
western countries [2,3]. While obesity is known to have many physiological consequences, the psychopathology
of this condition has not featured prominently in the literature. Overweight children
have increased odds of experiencing poor health related quality of life, particularly
in the domains of psychosocial health, self-esteem and physical functioning [4]. Severely obese children and adolescents have been reported to have lower health
related quality of life than children and adolescents who are healthy and to experience
a similar quality of life as those diagnosed with cancer [5]. Cross sectional data has also demonstrated a relationship between depressive symptoms
and body mass index (BMI) scores in pre-adolescent girls [6]. Overweight adolescents are more likely to be socially isolated than their normal
weight counterparts [7]. Of more concern however is the evidence [8] that teasing about weight body has been consistently associated with high depressive
symptoms and thoughts about attempting suicide in school children. Collectively, these
findings have created a need for clinicians and researchers to address issues that
are related to the long-term well-being of clinically obese young people. Without
intervention, many of these negative feelings can persist into adulthood and further
diminish quality of life and psychosocial health. The psychological needs of obese
adolescents are unlikely to be met fully by clinicians or health professionals and
exercise is not typically part of most rehabilitation programmes for obese young people.
Evidently, it is important that interventions be offered to obese adolescents as part
of their rehabilitation process so that they are able to participate in society to
the same extent as their non-obese peers.

The health benefits of a physically active lifestyle are well documented [9] and body weight has been found to be associated with increased risk of hyperlipidemia,
hypertension, insulin resistance and diabetes in later life [10]. Furthermore, physical activity for young people can contribute to the enhancement
of psychological and social well-being [11]. Indeed, the value of such activities should not be underestimated given that research
has consistently demonstrated that involvement in physical activity and exercise can
positively improve the mental and social health of young people [12-16]. While the use of exercise as an intervention to promote psychological health outcomes
has not been extensively investigated using RCT methodologies with obese children,
some preliminary evidence [17,18] has indicated that participation in weight loss camps that involve physical activity
can influence these outcomes. Such studies are few in number however, and typically
have been poorly controlled. Where studies [19] have included psychological variables, these have not been designated as primary
outcomes measures. A significant number of studies [19-23] have been based around weight loss programmes, such as restricting calorific intake
and low fat diets, which, in themselves, might be a sources of distress in young people
who are obese. Furthermore, although few studies have included waiting-list control
groups [22], to our knowledge no published randomised controlled trial (RCT) has included an
equal contact attention-control in an attempt to account for any attention effects
that might be associated with different types of lifestyle or behavioural change interventions
in this population. Research is also lacking on ways to tailor interventions to the
needs and interests of clinically obese young people, which is perhaps partly attributable
to the lack of detailed information provided by previous authors concerning their
intervention approaches.

Interventions that address both the physical and psychological concerns associated
with obesity are warranted. Using a randomised attention controlled methodology the
Sheffield Obesity Trial (SHOT) was designed to evaluate the efficacy of exercise therapy
as an intervention for improving both mental and physical health outcomes in obese
young people. The primary trial hypothesis was that the exercise therapy intervention
would lead to changes in participants' mental health and physical activity behaviour.
By implication, these changes in physical activity behaviour might also translate
into reductions in participants' BMI scores at follow-up.

Methods/design

Study aims

The primary aim of SHOT is to examine the effects of a supervised exercise therapy
intervention in young people who are obese.

Study design and setting

SHOT is a pragmatic randomised controlled trial where obese young people aged 11–16
years are randomised to receive exercise therapy, usual care or an attention-control
intervention. The study sample will consist of adolescents who have been referred
to a children's hospital in the United Kingdom (UK) for evaluation of obesity or via
community and media advertisements publicising the study. Participants recruited by
community adverts will have their medical eligibility to enter the trial confirmed
by one of the study paediatricians (third and fourth authors). In order to facilitate
recruitment and retention a £25 sport store voucher will be given to participants
at the end of the intervention phase and a contribution of £2.50 towards travel expenses
will be made per visit.

Ethical considerations

Full ethical approval for this study has been obtained from the South Sheffield Local
Research Ethics Committee. Written informed consent from all participants and their
parents will be sought prior to their enrolment into the study. Participants will
be asked to attend the dedicated project exercise facility for a familiarisation session
with their parents before entering the trial

Study interventions

The exercise therapy sessions will take place in a dedicated project exercise therapy
room housed at an English University. All exercise therapy sessions will take place
one-to-one with the second author and last approximately 1 hr. Participants will be
offered a range of aerobic exercise modalities, such as stepping, cycling, seated
rowing, the dance mat and walking, and asked to exercise intermittently for 30 minutes,
three times per week for eight weeks. The intermittent exercise will consist of a
4 minute warm up followed by four 4 minute bouts of moderate intensity exercise at
40–59% of heart rate reserve (%HRR) with 2 minute rests between each bout and 4 minute
warm down. Mini games will also be included, primarily designed with fun in mind;
they will also provide participants with the opportunity to experience personal development
throughout the programme and introduce a small self-referenced competitive element
into the sessions. Heart rate will be measured during the last minute of each 4 minute
bout of exercise. Once participants have completed the eight week exercise intervention
they will be given an individualised (moderate intensity) home exercise programme
to follow for a further six weeks. It is hoped that the follow-up phase will help
participants to move towards becoming autonomous exercisers and empower them to continue
to commit to a lifestyle that involves regular aerobic exercise. During the exercise
therapy sessions participants' rating of perceived exertion will be measured using
the Pictorial Children's Effort Rating Table (PCERT) [24,25]. This instrument uses pictures as well as descriptive language, and has been found
to reflect the changing physiological demands of given exercise tasks; higher ratings
as measured by the PCERT corresponded with increases in exercise intensity [25]. Participants will be asked to estimate the exertion they feel on a 10-point scale
as illustrated in Figure 1.

Motivating obese children to exercise cannot be achieved in the same way as for children
of normal weight [26]. Not only are obese children physiologically different from children of normal weight,
but they also have demonstrated significant emotional differences [27]. Additionally, as obese individuals tend both to be sedentary and to have had poor
experiences with exercise [28], short bouts of intermittent exercise are considered most appropriate for this population.
One of the common barriers to achieving long-term exercise habits in obese young people
is the duration of physical activity that is often expected of them. Moreover, this
can be a daunting task for these children and such high exercise demands are unlikely
to be enjoyable or sustainable; this is particularly likely to be the case when obese
individuals are in the early phases of adopting a physically active lifestyle. As
the primary goal of this study was mental health outcomes, and not necessarily weight
loss per se, intermittent exercise was considered most likely to provide opportunities
for participants to experience a sense of accomplishment. The Department of Health
[29] in England has recently advocated the use of short bouts of exercise accumulated
throughout the day to gain health benefits.

Exercise counselling will be an integral part of the exercise sessions. It is hoped
that exercise counselling will provide participants assigned to the exercise therapy
group with the necessary knowledge and the psychological skills and tools to sustain
changes in their exercise behaviour. This trial will use the Transtheoretical Model
(TTM) [30] as the guiding framework for the exercise counselling to promote positive exercise
attitudes and experiences. In line with TTM, weeks 1–4 will focus on cognitively based
intervention strategies such as cognitive reappraisal and consciousness raising. During
weeks 5–8, more behaviourally based interventions will be introduced, for example,
goal setting, self-monitoring and finding social support. Participants will follow
a broad structured curriculum of topics over the course of the intervention. Detailed
descriptions of the strategies and techniques to be used during exercise counselling
are outlined in Table 1. Weight loss per se will not be explicitly discussed with participants and no weight loss targets will
be set, although sensible eating habits will be discussed and encouraged as part of
the exercise therapy intervention.

An attention-control intervention (body-conditioning) has been included in this trial
in an attempt to control for any attention effects that might occur in participants
assigned to the exercise group. This is particularly important in the current study
because the exercise therapy group will receive one-to-one sessions with the researcher.
Any attention-control condition must be relevant and meaningful, particularly when
used with young people. We have tried to achieve this by presenting an alternative
'exercise' group that does not involve aerobic exercise but an apparently different
type of exercise in the form of body conditioning activities. Thus, like the exercise
therapy group, participants assigned to the attention-control group will attend the
project exercise facility for 1 hr three times per week for eight weeks. HR will be
maintained below 40% HRR. Attention-control sessions will include activities such
as stretching, posture, twister, as well as static juggling and catching tasks. The
format of the attention-control sessions will be similar to the exercise therapy sessions;
involving four 4 minute body-conditioning activities with 2 minute rest between activities.
During the remainder of the session, other sedentary activities and games such as
pool, darts and table football will be included to help facilitate adherence to the
intervention and to make the sessions interesting and engaging. The attention group
will be given a home body-conditioning programme to follow for six weeks. The attention-control
group will be asked to otherwise continue with their lifestyle as normal throughout
the study and will not receive exercise counselling.

The usual care comparison group will be asked to continue with their lives as usual;
they will be given the opportunity to complete exercise sessions at the centre once
they had completed the study.

Determining eligibility for the study

Participants will be recruited according to the following criteria: (1) clinically
obese and aged 11–16 years (Body Mass Index Centile > 98th UK standard) [31]; (2) no medical condition that would restrict ability to be active three times per
week for eight weeks; and (3) not diagnosed with insulin dependent diabetes or receiving
oral steroids.

Randomisation

A researcher from an independent University will perform the randomisation procedures
by allocating participants to groups according to a computer generated random list.

Outcome measures

Physical self-perceptions

Physical self-perceptions served as the primary outcome measure. The Physical Self-perception
Profile (CY-PSPP) was originally developed by Fox and Corbin [32] and later adapted for use with children by Whitehead [33]. The inventory contains six 6-item subscales; Sport/Athletic Competence, Attractive
Body Adequacy, Condition, Strength, Physical Self-worth. The Children and Youth Physical
Self-perception Profile (CY-PSPP) assesses the extent to which young people view themselves
as competent in variety of physical domains. Each is devised in a structured alternative
format on a scale between 1 (low score) and 4 (high score).

Self perceptions

Items measuring social acceptance, scholastic competence and global self-worth are
to taken from Harter's Self Perception Profile for Adolescents [34]. The social acceptance subscale assessed the degree to which the adolescent feels
accepted by their peers, feels popular, has lots of friends, and feels that he/she
is easy to like. The scholastic competence items tap participants' perception of their
competence or ability within the school context. The global self worth subscale assesses
the extent to which participants like themselves as a person and the way they are
living their lives. Each subscale contains six items devised in a structured alternative
format on a scale between 1 (low competence) and 4 (high competence).

Depression

Depression will be assessed using the Children's Depression Inventory (CDI) [35]. The CDI is a 27-item self-rated symptom-orientated scale suitable for school-aged
youngsters and adolescents. For each item, the child is asked to endorse one of three
statements that best describe how he or she has typically felt over the past two weeks.
Each response is scored as 0 (asymptomatic), 1 (somewhat symptomatic), or 2 (clinically symptomatic), contributing to a total CDI score that can range from 0–54.

Affective responses

In the absence of any exercise specific measures of affect for use with clinical child
populations, items used by Ebbeck and Weiss [36] in sports settings will be included in this study. Participants responded to two
subscales that assessed positive and negative affective responses over the previous
week. On a scale between 1 (not at all or very slightly) to 5 (extremely) participants
are asked to indicate the degree to which a series of positive and negative adjectives
described how they have felt over the previous week.

Physical activity

The Physical Activity Questionnaire for Adolescents [37] will be used to collect detailed information about participants' involvement in different
physical activities. Specifically, participants are asked about their involvement
in (1) various physical activities in their spare time, (2) physical education, (3)
lunchtime physical activities, (4) extra-curricular physical activities, (5) evening
physical activities and (6) weekend activities. Each physical activity component is
scored on a scale between 1 (not involved) to 5 (involved 5–7 times per week.

Anthropometrics, flexibility and aerobic fitness

As treadmill protocols engage a larger muscle mass than cycling and peak VO2 scores are more likely to be limited by central rather than peripheral factors [38], the poorly fit category of the modified Balke protocol [39], will be used to assess aerobic fitness. Distance walked in miles was recorded. Height
was measured to the nearest completed 0.1 cm using a wall-mounted stadiometer. Weight
was measured to the nearest 0.1 kg using a balance scale. From these values BMI (weight(kg)/(height(m)2) will be calculated and the standard deviation Score (SDS – or Z score) derived from
the UK 1990 Data [40]; a child whose BMI exceeds the 98th percentile for age and sex according to UK reference data in 1990 will defined as
obese for the purposes of this study. Severe obesity will be defined as a BMI SDS
of >+3.5 (or an adult-equivalent BMI of >40). Participants' trunk and hamstring flexibility
will be assessed using the modified Acuflex I flexibility test, which allows for variations
in participants' arms and legs.

Assessment of outcomes

The main study outcomes will be assessed at baseline, as well as four (intervention
midpoint) and eight weeks (end of intervention) from baseline. Participants will be
reassessed on outcome measures at the end of the home intervention phase (approximately
five months from baseline). To provide evidence on the possible longer-term effects
of exercise therapy, a final assessment will be completed approximately seven months
from baseline (see Figure 2). The second author will perform all assessments and deliver the exercise therapy
and body conditioning sessions. Demographic data, including age and ethnicity and
current physical activity participation will be collected at baseline. Adherence to
the exercise therapy and attention-control interventions will also be monitored.

Sample size considerations

As there has been a lack of published studies in this field power calculations have
been based upon related review studies in the field of exercise and mental health.
Power calculations are based upon physical self-perceptions as the primary outcome
measure; (predicted effect size = 0.6, providing 80% power, p < 0.05) indicating 30
participants would be needed for each group (n = 90). A 25% dropout rate has been
assumed at eight weeks from baseline indicating that 122 participants might need to
be recruited.

Statistical analysis

Differences in primary and secondary outcomes between control and intervention groups
will be compared using intention to treat analysis. Imputation methods will be used
to assess data losses through level drop out and loss to follow up. All results will
be reported as means and 95% confidence intervals.

Time plan for the study

Participant recruitment began in April 2002 and by January 2006 all participants will
have completed the trial and follow-up assessments of outcomes.

Competing interests

The author(s) declare that they have no competing interests.

Authors' contributions

Amanda Daley and Jerry Wales were responsible for identifying the research question
and contributing to drafting the research protocol. Robert Copeland has contributed
to the development of the protocol as member of the research team. All authors were
responsible for the drafting of this paper and have read and approved the final version.

Acknowledgements

This study was supported by a research award to the first and fourth authors from
The Health Foundation: grant number 2402/957.

References

Chinn S, Rona R: Prevalence and trends in overweight and obesity in three cross sectional studies of
British children, 1974–1994.

Mutrie N, Parfitt G: physical activity and its link with mental, social and moral health in young people. In In Young and Active? Young People and Heath-enhancing physical Activity: Evidence
and Implications. Edited by Biddle SJH, Cavill N, Sallis J. London. Health Education Authority; 49-68.

Brown JD, Seigel JM: Exercise as a buffer of life stress: A prospective study of adolescent health in the
pediatric population.